A journal published in the American Physical Society illustrates the optical (light) levitation of nano-particles spinning at one billion rotations per second. This experiment allowed scientists to determine the amount of “friction” in a vacuum by switching the direction of laser beams to observe how long it took the system to respond.
The new discovery could have implications for bio-medicine, optics, and electronics. You’d surprised at how many fields rely on the behavior of quantum mechanics to function properly. The bottom line is that will only increase in relevance with the coming age of next generation quantum technologies, including quantum computing.
During optical levitation gravity is countered by the upward force of photons from a parallel laser beam. With enough energy and accuracy you can levitate nano particles indefinitely creating what is called an “optical trap”. Nano-particles are larger then a molecule but smaller then bulk materials. They range between 1 to 100 nanometres. Scientists performed this procedure in a vacuum where they suck as much matter out of an area as possible.
A long time ago researchers hypothesized that the vacuum would be devoid of energy due to the removal of all matter and subatomic particles. However, what they eventually discovered was more complicated. Instead, when they got down to this ground state of reality subatomic particles would appear to pop in and out of existence.
Since conventional relativity does not allow for disappearing matter the behavior of a vacuum can only be explained through quantum mechanics, a branch of physics normally relegated to the very small. Thus the subatomic froth in a vaccuum was called “quantum fluctuations”
Their experiment was originally designed to demonstrate how light’s energy can move particles around but they ended discovering something more profound. Using this form of levitated optomechanics, two different teams performed similar experiments, independently.
In this first experiment scientists used laser beam to levitate the nano-particles in a vacuum in order to see how they would react in response to light.
The nano-particles began to spin around each other faster and faster until they reached billions of rotations a second. What they discovered is that nano-particles appear to spin much faster in a vacuum because the speed of rotation begins to outpace the binding energy that holds atoms together inside the nano-particle.
In the second experiment scientists used silicate nano-particles and ended up with a similar result. They also experimented further by switching the polarization of the laser beam to observe how long it would take the rotation to correct itself.
That allowed them to determine the exact “friction” present in the vaccuum – a part of space previously thought to be entirely empty due to scientists purposefully removing all known matter from the area (liquid gas solids
cover photo: example of silica nanoparticles, ames laboratory